PROJECT ABSTRACT/SUMMARY Kidney transplantation is the preferred modality of treatment for end-stage renal disease (ESRD), as it improves quality of life and survival for patients with ESRD. However, racial and ethnic disparities in access to kidney transplantation are present in adults and children with chronic kidney disease. The lower access of black and Hispanic adults to kidney transplant has been ascribed to late referral for nephrology care, delayed referral for transplant evaluation, lower socioeconomic status, and differences in cultural beliefs or attitudes surrounding organ transplantation. However, the fact that similar racial and ethnic disparities are also present in children (who have better access to healthcare than adults, and for whom transplantation is the standard ESRD treatment modality) suggests that there may be additional barriers that contribute to these disparities. For example, some studies have suggested that chronic kidney disease (CKD) progresses more rapidly in black and Hispanic patients, which could shorten the time available for transplant evaluation, waitlisting, and preemptive surgery during the advanced stages of CKD (prior to dialysis). In addition, since obesity is more prevalent in racial and ethnic minorities in the United States, and most transplant centers have body mass index criterion for transplantation and kidney donation, this policy may disproportionately disadvantage black or Hispanic recipients despite the absence of solid evidence that long-term allograft outcomes are worse in obese recipients. Donor perceptions regarding their own health, or transplant center's assessment of donor suitability, may also differ by donor race or ethnicity. Thus, the objective of this proposal is to evaluate disparities in transplant access in both adults and children within the context of medical risk factors (and policies surrounding these risk factors) that may disadvantage black or Hispanic patients, compared to their non-Hispanic white counterparts. In Aim 1, we propose to examine whether there are differences in the time spent in the advanced stages of CKD (stage 4 or 5) by race or ethnicity (when evaluation for waitlisting or transplantation typically occurs) using individual level data from four national CKD cohorts. In Aim 2, we propose to evaluate how body mass index may contribute to racial and ethnic disparities in access to transplantation or suitability for kidney donation using data from the United States Renal Data System (recipients) and University of California San Francisco [UCSF] (donors). In Aim 3, we propose to establish a prospective study of potential living kidney donors to compare donor perceptions of their health with objective measures of donor risk and the transplant center's perception of donor suitability by race and ethnicity. UCSF is well-suited for the conduct of this proposal, given that it is one of the largest transplant centers in the US, performing 300-350 kidney transplants (including about 150 living donor transplants) annually. Our study will inform whether policy changes are needed to improve parity in access to kidney transplantation and will facilitate the design of additional strategies to enhance organ donation among racial and ethnic minorities.